Linus Björnstam
4f48282314
gui-update is a plain function, so it cannot wait. It returns the work to do as values. A command is an (Event %m), synced in a fiber of its own, whose answer is the next message. A subscription is a source of messages that the model asks for: after each update the app starts the new ones and cancels the ones that are gone, by key. every sends a message on a timer, and subscription takes a source of one's own. The fibers belong to the app's scope and post their messages to the UI thread, so gui-update and view only run there. Closing the window cancels them. The prelude's path macros already use the name update, hence gui-update. 🤖 Generated with [ECA](https://eca.dev) (anthropic/claude-opus-4-8) Co-Authored-By: eca-agent <git@eca.dev>
35 lines
1.2 KiB
Text
35 lines
1.2 KiB
Text
;; This Source Code Form is subject to the terms of the Mozilla Public
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;; License, v. 2.0. If a copy of the MPL was not distributed with this
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;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
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;; bjogui/examples/counter.bjo — a counter and a greeting in a window.
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;;
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;; bjo run examples/counter.bjo
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(import (std prelude))
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(import (bjogui view))
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(import (bjogui app))
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(type (: Msg (Union Inc Dec (: Typed string))))
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(type (: Model (Record (: count int) (: name string))))
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(: gui-update (-> Msg Model (Tuple Model (List (Event Msg)))))
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(defun (gui-update msg m)
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(next
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(match msg
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(Inc (record-set m (count (+ (.count m) 1))))
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(Dec (record-set m (count (- (.count m) 1))))
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((Typed s) (record-set m (name s))))))
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(: view (-> Model (View Msg)))
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(defun (view m)
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(column #:spacing 8.0 #:margin 16.0
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(text-input (.name m) Typed #:placeholder "Your name")
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(text #"Hello, ${(if (string-empty? (.name m)) "stranger" (.name m))}!" #:size 18.0)
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(row #:spacing 8.0
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(button "-" Dec #:width 40.0)
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(text #"${(.count m)}" #:size 18.0 #:margin 4.0)
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(button "+" Inc #:width 40.0))))
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(defun (main)
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(run-app (Model (count 0) (name "")) gui-update view #:title "Counter" #:width 320.0 #:height 200.0))
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